The invention is in the field of automatically configuring integrated circuit devices.
For a network system to operate, devices in a network must communicate their status to each other under various circumstances. For example, if device A wishes to transmit data to device B, device A may need to know whether device B can currently receive data. In this circumstance, and many others, a device may first need to know whether another device is in an active state, or has an active status. In some networks, routing tables list all active devices in the network. If a device has not been active in receiving or transmitting data for some period, such as when the device is powered down (in a xe2x80x9csleepxe2x80x9d state), the device may be removed from the routing table. When a device is removed from the routing table, the router that removed it no longer knows the device exists. To prevent this from occurring, some network devices periodically transmit data over the network to inform other network devices that they are still on the network. The data may be so-called xe2x80x9ckeep-alivexe2x80x9d packets formatted according to a predetermined protocol.
One way of using keep-alive packets is to store the packets in a transmit first-in-first-out (FIFO) buffer that is used for staging data to be transmitted over the network. The keep-alive packets are periodically transmitted when the network device is in a sleep state. A shortcoming of this scheme is that, should the power to the network device temporarily be lost, for example as a result of a power surge, the FIFO buffer is emptied. When power is restored to the network device and the network device enters a sleep state, the device may be removed from network routing tables because no keep-alive packets are transmitted.
Other data besides keep-alive packets may be stored in the transmit FIFO for use in a sleep state. For example, alert packets may be transmitted from the transmit FIFO to a remote network component in the event of abnormal conditions detected in the network device. Wake up patterns may also be stored in the transmit FIFO. Wake up patterns are patterns of data that are compared to data entering the network device, for example through a receive FIFO. The wake up patterns match data that, when received by the network, requires a response from the device. When a match is found between the wake up patterns stored and the data received, an appropriate signal is sent to cause the network device to exit the sleep state.
Prior schemes for storing status data in the transmit FIFO have several disadvantages. The status data is typically stored in the transmit FIFO by network driver software. The types of data stored are limited in that, if it is desired to change the data stored, the network driver must be changed. Another disadvantage is that requiring the network driver to load the status information increases network driver overhead. Another disadvantage is that status data lost from the transmit FIFO on power loss is usually not restored when power is restored.
A method and apparatus for automatically loading status information into a network device is disclosed. One embodiment comprises an apparatus in a network device that enters a sleep state under particular conditions. The apparatus comprises a buffer for storing data that is to be transmitted. The apparatus also comprises a memory device that stores configuration data for the apparatus. The configuration data is loaded to the apparatus each time the network device is powered up. In one embodiment, keep-alive data is stored in the memory device so that it too will be loaded to the apparatus each time the network device is powered up. In one embodiment, the apparatus is for communicating with other devices on the network and comprises control circuitry that controls communication between the network device and the other devices on the network. The apparatus further comprises a memory device that stores configuration data for the control circuitry, wherein at least a portion of the configuration data is loaded into the control circuitry upon initialization of the network device. The apparatus further comprises a buffer that stores keep-alive data that is transmitted to a plurality of the other devices in the network to refresh the presence of the network device in the network, wherein the keep-alive data is loaded into the buffer from the memory device upon initialization of the network device.